we have a 28' enclosed at work, they use it for big events (off-road equipment). However, the boss has, from time-to-time, hauled his tractor with it. This 28' trailer is 1' extra height. Most are around 6' floor to ceiling, this one is 7'. It is not an uncommon setup with the 1' extra height. It adds more expense though, to an already pricey trailer. Ours at work is a Cynergy2 trailer. They're "ok", but I am not really that impressed with them. Lot of cut corners. If I were in the market for another trailer, I would probably try my best to avoid that brand.
Keep this in mind. The trailer with tractor may not be all that heavy, but a big box takes a TON of power to pull it at freeway speeds. Adding 1' extra height makes it even harder to pull. Get a V nose if possible, that helps but they still need a lot of power to pull them at speed. My truck is an F250 diesel (7.3) and on the floorboard, it will run 77 mph on flat ground with no wind pulling my 26' standard height trailer with race car in it. Without the car in it (empty), it runs 77 mph flat footed. It's not the weight, it's the aero drag. Just gives you something to think about.